1. Field of the Invention
The present invention relates to a malfunction detecting apparatus, especially having a plurality of voltage detecting devices and a malfunction detecting device. The plurality of voltage detecting devices detects each voltage between both terminals of unit cells, which are secondary-battery types, forming the block, and is provided corresponding to each block of a plurality of blocks divided from a battery pack having a plurality of unit cells connected in series with each other. The malfunction detecting device detects an abnormal condition of the voltage detecting device based on each voltage between both terminals of each unit cell detected by the plurality of voltage detecting devices.
2. Description of the Related Art
Conventionally, as an above mentioned malfunction detecting apparatus, a voltage detecting apparatus for a battery pack described in patent document 1 is proposed. The voltage detecting apparatus for the battery pack has a plurality of voltage detecting circuits (voltage detecting devices) and a total voltage detecting circuit and a controller (a malfunction detecting device). The plurality of voltage detecting circuits is arranged corresponding to each block of a plurality of blocks divided from the battery pack having a plurality of unit cells connected in series with each other. The plurality of voltage detecting circuits detects each voltage between both terminals of unit cells included in the block corresponding thereto.
The total voltage detecting circuit detects the voltage between both terminals of the battery pack. A communication line is arranged between each of the plurality of voltage detecting circuits and the controller, and it is capable of communicating with each of the plurality of the voltage detecting circuits and the controller. In addition, a communication line is arranged between the total voltage detecting circuit and the controller, and it is capable of communicating with the total voltage detecting circuit and the controller.
The controller detects an abnormal condition of the voltage detecting circuit by comparing the voltage between both terminals of the battery pack calculated from a sum of voltages between both terminals of all unit cells detected by the plurality of voltage detecting circuits and the voltage between both terminals of the battery pack detected by the total voltage detecting circuit.    Patent document 1:    Japan published patent application 2003-243044    Patent document 2:    Japan published patent application 2000-74786